One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,8)(3,6,4,7)(9,10,15,12)(11,13,18,16)(14,17,23,20)(19,21,24,22)(1,2)(3,6)(4,7)(5,8)(9,11,15,18)(10,16,12,13)(14,19,23,24)(17,22,20,21)(25,26,31,30)(27,35,38,32)(28,33,37,39)(29,34,36,40)(1,3,5,4)(2,6,8,7)(10,12)(11,18)(17,20)(19,24)(25,27)(26,32)(28,36)(29,37)(30,35)(31,38)(33,34)(39,40)(1,3,5,4)(2,6,8,7)(9,12,15,10)(11,13,18,16)(14,20,23,17)(19,21,24,22)(25,28,31,37)(26,33,30,39)(27,36,38,29)(32,34,35,40)(1,3,5,4)(2,6,8,7)(9,13)(10,11)(12,18)(14,22)(15,16)(17,24)(19,20)(21,23)(25,29,31,36)(26,34,30,40)(27,37,38,28)(32,33,35,39)(1,4,5,3)(2,7,8,6)(9,14,15,23)(10,17,12,20)(11,19,18,24)(13,21,16,22)(25,30,31,26)(27,35,38,32)(28,39,37,33)(29,34,36,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.